In general, inkjet printing machines or printers include at least one printhead that ejects drops or jets of liquid ink onto an image receiving member, which may be media, either in sheet or web form, or a rotating intermediate member from which the ink is later transferred to media. A phase-change inkjet printer employs phase change inks that are solid at ambient temperature, but transition to a liquid phase at an elevated temperature. The melted ink can then be ejected by a printhead to form an ink image on the image receiving member. When the image receiving member is a rotating intermediate member, a layer of release agent is applied to the intermediate imaging member, such as a rotating drum or belt, to facilitate the transfer of the ink image to a receiving substrate, such as a sheet of paper, as the substrate passes through a nip formed between a transfer roller and the intermediate imaging member.
In various modes of operation, ink is purged from the printheads to ensure proper operation of the printhead. During purging, ink is typically forced through the ink pathways, chambers, and out of the inkjet apertures in the faceplate of the printhead by pressure applied to an ink reservoir in the printhead. This pressure urges debris and/or air bubbles out of the printhead along with some of the ink. Such clearing action enables malfunctioning inkjets to recover the ability to eject ink properly again. The purged ink flows down and off the face of the printhead, typically into a waste tray positioned below the printhead for removal from the printer or into an ink collecting tray mounted on the bottom of the printhead for reuse in the printer.
Printers have limited space in which to mount an ink collecting tray to the bottom of the printhead. The ink collecting tray must be positioned such that the tray does not interfere with the rotating imaging drum in an indirect printer or the media web in a continuous direct printer, both of which are positioned adjacent to the printhead to enable the printhead to eject ink onto the drum or web. Thus, to avoid interfering with the drum, the ink collecting tray can extend only slightly beyond the printhead face in an indirect printer. In a continuous direct printer, the ink collecting tray must be positioned substantially even with the printhead face to avoid interference with the media web. Purged ink that flows rapidly down a printhead face can miss the ink collecting tray or splash out of the tray and land on the drum or other components of the printer. Previously known printheads included drip bibs to catch the purged ink and direct it to the waste or ink collecting tray. However, the drip bibs add components to the construction of a printhead and require space to accommodate the bib profile within the printer. Thus, improved handling of ink purged from a printhead would be beneficial.